Scientific Opinion on the safety and efficacy of the product Cylactin® (Enterococcus faecium) as a feed additive for chickens for fattening

Zootechnical additive, gut flora stabilisers, Cylactin®, Enterococcus faecium, kanamycin resistance, chickens for fattening, safety, efficacy, compatibility
First published in the EFSA Journal
9 July 2010
22 June 2010
Scientific Opinion

Cylactin® is a product consisting of viable cells of Enterococcus faecium. The product strain was found to beresistant to kanamycin. A detailed study of the nature of kanamycin resistance demonstrated the absence ofknown acquired genes coding for aminoglycosides-modifying enzymes. Two genetic determinants, theaminoglycoside acetyltransferase gene aac(6’)-li and the gene sfkmr, both intrinsic to E. faecium, were shown tocontribute to the resistance to kanamycin. In the view of the FEEDAP Panel, the resistance of this strain of E.faecium is most likely to be caused by an unknown mechanism that potentiates the effect of the sfkmr gene, andnot by acquisition of resistance genes, and thus is not a cause for concern. When used at 100 times therecommended level, Cylactin® did not show any adverse effect on performance or mortality of chickens forfattening. Therefore, the additive is safe for the target animals at the proposed conditions of use. E. faeciumNCIMB 10415 is free of known enterococcal virulence factors. No other concerns for consumer safety wereidentified. Cylactin® is not a skin/mucosal irritant or skin sensitiser. As the product is formulated with a largeparticle size and the dusting potential is low, inhalation exposure of users will be minimal. Cylactin® isefficacious in chickens for fattening as demonstrated in three trials showing an increase in final body weightwhen diets were supplemented at or close to the minimum recommended dose (0.3 x 109 CFU/kg feed).Cylactin® is compatible with decoquinate, monensin, robenidine, diclazuril and semduramycin.

Panel members at the time of adoption
Gabriele Aquilina, Georges Bories, Paul Brantom, Andrew Chesson, Pier Sandro Cocconcelli, Joop de Knecht, Noël Albert Dierick, Mikolaj Antoni Gralak, Jürgen Gropp, Ingrid Halle, Reinhard Kroker, Lubomir Leng, Sven Lindgren, Anne-Katrine Lundebye Haldorsen, Alberto Mantovani, Miklós Mézes, Derek Renshaw and Maria Saarela.
Panel on Additives and Products or Substances used in Animal Feed
EFSA Journal 2010; 8(7):1661
Question Number
On request from
European Commission
Competing interests
One member of the Panel did not participate in the discussion on the subject referred to above because of potential conflicts of interest identified in accordance with the EFSA policy on declarations of interests.